Device for adjusting angle of inclination of reference mirror for interferometer

ABSTRACT

A device for adjusting the angle of inclination of an interferometer reference mirror having a mirror holding member connected to a support member which is adapted to be slideably connected to an objective lens tube. The angle of inclination of the mirror holding member with relation to the support member and the objective lens is adjusted by adjusting members connecting the mirror holding and support members. The device is made slidable relative to the objective lens, so that the adjustment of the spacing and the direction of the interference fringes is carried out without damaging the specimen and the reference mirror. The replacement of the reference mirror and the objective lens may be made easily. The adjustment of the holding member for obtaining the interference fringes by multi-beam interference may be accomplished easily. Further, the device may be applied not only to multi-beam interferometers but also to the objective lens part of a microscopes.

United State Kato et al.

anoeteeg la Jan. 9, 1973 DEVICE FOR ADJUSTING ANGLE OF INCLINATION OFREFERENCE MIRROR FOR INTERFEROMETER Jinichi Kato; Toshiharu Shimizu,both of Tokyo, Japan Assignee: Nippon Kogaku K.K., Tokyo, Japan Filed:Aug. 26, 1970 Appl. No.: 67,070

Inventors:

Foreign Application Priority Data Aug. 30,1969 Japan ..44/s1s97 US. Cl..356/109, 350/202 Int. Cl. ..G01b 9/02 Field of Search ..350/202;

References Cited UNITED STATES PATENTS Primary Examiner-John K. CorbinAttorney-Harry G. Shapiro [57] ABSTRACT A device for adjusting the angleof inclination of an interferometer reference mirror having a mirrorholding member connected to a support member which is adapted to beslideably connected to an objective lens tube. The angle of inclinationof the mirror holding member with relation to the support member and theobjective lens is adjusted by adjusting members connecting the mirrorholding and support members. The device is made slidable relative to theobjective lens, so that the adjustment of the spacing and the directionof the interference fringes is carried out without damaging the specimenand the reference mirror. The replacement of the reference mirror andthe objective lens may be made easily. The adjustment of the holdingmember for obtaining the interference fringes by multi-beam interferencemay be accomplished easily. Further, the device may be applied not onlyto multipart of a microscopes.

5 Claims, 3 Drawing Figures PATENTEDJAN 9 I973 BY TOSHIHARU SHIMIZUATTORNEY DEVICE FOR ADJUSTING ANGLE OF INCLINATION OF REFERENCE MIRRORFOR INTERFEROMETER BACKGROUND OF THE INVENTION The present inventionrelates to a device for adjusting an angle of inclination of a referencemirror for interferometers.

In the conventional interferometer, especially in a multi-beaminterferometer, various measurements are made by utilizing thephenomenon, that the interference fringes which are obtained due to aslightly wedge-shaped space between a specimen and a reference mirror,appear in the horizontal plane with the spacing between the fringesbeing M2 (half the wavelength of the reflected light). To obtain suchinterference fringes, the spacing between the specimen and the referencemirror must be extremely small and a very extremely small angle must beformed therebetween. Therefore, the conventional device for such Spacingand angular adjustment had the following defects:

I. For spacing adjustment, first the reference mirror is put in contactwith the specimen and then moved away therefrom so as to provide a verysmall spacing therebetween so that the specimen or reference mirror orboth tend to be damaged if considerable care is not exercised. Further,when the specimen is soft, it tends to be deformed;

II. The device for adjusting the angle of inclination of the referencemirror is made integral with the main body of an interferometer so thata change in magnification is inconvenient because the objective lens isalso incorporated in the main body, and moving the objective lens movesthe reference mirror. The changes of various types of objective lensesand reference mirrors are also very inconvenient.

III. The device of the conventional type is generally designedexclusively for use on interferometers so that it may not be employed inan optical instrument having the same fundamental optical system as thatof the interferometer such as metallurgical microscopes, dissectingmicroscopes, etc; and

IV. The conventional device is complex in operation and adjustment.

SUMMARY OF THE INVENTION An object of present invention is to eliminatethese defects.

The invention comprises a supporting member which is fitted over anobjective lens tube, a reference mirror holder holding a referencemirror, and adjustment members interposed between the supporting memberand the reference mirror holding member to couple both of them and toincline the reference mirror holding member with relation to thesupporting member.

According to the present invention, the objective lens is not madeintegral with the reference 'mirror inclination adjustment device, butinstead is slidable relative to the objective lens so that undesiredforce is not applied to the specimen, the objective lens or thereference mirror when the spacing between the fringes and the directionthereof are adjusted so that the damage to the specimen and thereference mirror may be prevented. Focusing may be made independently ofthe reference mirror inclination adjustment device and the specimen, andthe replacement of the reference mirror and the objective lens may beeasily accom plished. Depending upon the hardness of the specimen, thepressure applied thereto may be varied thereby preventing thedeformation of the specimen. The adjustment for obtaining theinterference fringes by multi-beam interference may be accomplished in asimple manner, The device of the present invention may be applied notonly to the multi-beam interferometer but also to a metallurgicalmicroscope so as to determine the surface smoothness and to measure thelength by multi-beam interference. The device of the present inventionis compact in size, simple in construction and manufacture andinexpensive.

BRIEF DESCRIPTION OF THE DRAWING The present invention will be moreapparent from the following explanation, referring to the embodimentshown in the accompanying drawings in which:

FIG. 1 is a front sectional view of one embodiment of the presentinvention;

FIG. 2 is a view looking in the direction of the arrows A-A in FIG. 1;and

FIG. 3 is a side view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, FIG. 2,and FIG. 3, an objective lens holder 2 is detachably fitted into a mainbody 1 of a microscope through a dovetail joint. Reference numeral 3designates a tube for an objective 3; 4, a guide pin extended from theobjective lens tube 3; 5, a supporting member, is fitted to theobjective lens tube, and is guided for vertical sliding movement by theguide pin 4; and 5 a guide slot into which the guide pin is fitted. Anadjustment handle 6 is in threaded engagement with an adjustment screw 7so as to slightly incline a reference mirror 13' to be described, theadjustment handle 6 being rotatably about the supporting member 5 whilethe adjustment screw 7 is vertically moved by rotation of the adjustmenthandle 6. Locknuts 8 fix the adjustment handle 6 to the supportingmember 5 for rotation. A hinge 7' serves to give a slight inclination tothe reference mirror 13' and together with the two adjustment handles 6,each has one end engaged to a reference mirror holder 9, to bedescribed, and its the other end mounted to the supporting member 5.Instead of the hinge 7 a third adjustment handle 6 may be employed. Theadjustment members are constituted by the adjustment handles 6, theadjustment screws 7, the locknuts 8, the hinge 7' and a stopper 10 to bedescribed.

Element 9 is a reference mirror holder, one end thereof fitted with thehinge 7' and the other two ends thereof provided with adjustment screws7 which are able to pivot slightly about the holder 9. The stopper l0prevents the rotation of the adjustment screw 7, and is fixed to thereference mirror holder 9. A spring 11 is interposed between thesupporting member 5 and the reference mirror holder 9 so as to removethe play between the adjustment handle 6 and the adjustment screw 7, Aweight 12 is detachably fixed over the holder 9 so that the suitableweight 12 may be used depending upon the hardness of a specimen. The

reference mirror 13 having the same reflectivity as that of the specimen14 is fixed to the holder 9 by means of a retaining ring 13, so that thereference mirror 13 may be readily replaced when damaged. The referencemirror inclination adjustment device is constituted by the supportingmember 5, the adjustment handles 6, the adjustment screw 7, the hinge 7the locknuts 8, the reference mirror holder 9, the stoppers 10, thespring 11, the weight 12, the retaining ring 13, and the referencemirror 13'.

Next the mode of operation will be described. The main body 1 of themicroscope is lowered toward the specimen 14 through focusing means (notshown) so as to place upon the specimen the reference mirror inclinationadjustment device. Next focusing may be made by the focusing means ofthe microscope (fine adjustment in practice) by shifting the main body1, the objective lens holder 2 and the objective lens 3' independentlyof the reference mirror inclination adjustment device. With thereference mirror inclination device placed upon or very close thespecimen 14, the interference fringes are formed because the distancebetween the two is of the order of M2. Thus, when focused correctly, theinterference fringes due to multibeam interference may be observed withhigh contrast. By adjusting the handles 6, the spacing between thefringes and the direction of the fringes may be arbitrarily variedbecause the angle of the reference mirror 13' relative to the specimen14 may be varied by the two adjustment handles 6. The objective lens 3'may be moved from the proper position for observation and independentlyof the reference mirror inclination adjustment device within the rangein the vertical direction in which the guide pin 4 may move in the guideslot of the supporting member 5 to provide a safe objective lens effect.Thus, focusing may be made with ease. Furthermore, the reference mirrorinclination adjustment device may be easily attached to and detachedfrom the objective lens tube 3. It is only necessary to provide theguide pin 4 in the tube or in the extreme case the objective lens tube 3may be fitted into the supporting member 5 without providing the guidepin 4 Therefore, multi-beam interference may be obtained in a simplemanner by using an ordinary objective lens.

When the main body 1 and the lens holder 2 are joined together throughan inclined dovetail joint, the replacement of the objective lenses andthe device may be made without causing any damage to the specimen.Furthermore, the device may be used for various types of objectivelenses having various powers.

What is claimed is 1. A device for adjusting the angle of inclination ofa reference mirror for interferometers comprising 0bjective lens holdingmeans; support means mounted on the objective lens holding means;cooperable guide slot and projection means provided by the objectivelens holding means and the support means for relative sliding movementin a direction parallel to the optical axis of the objective lens;reference mirror holding means; and adjusting means connecting thereference mirror holding means to the support means for adjustment ofthe angle of inclination of the reference mirror holding means withrespect to the support means and thereby with respect to the ob jectiyelens holding means.

2. The device for a ustmg the angle of inclination of a reference mirrorfor interferometers according to claim 1 wherein the objective lensholding means comprises a lens tube; wherein the support means includesa tubular portion surrounding the lens tube and the adjusting meanscomprises a member threadably connected to one of the reference mirrorholding means and support means and is pivotally connected to the otherof the reference mirror holding means and support means.

3. The device for adjusting the angle of inclination of a referencemirror for interferometers according to claim 2 wherein the adjustingmeans further comprise hinge means connecting the support means and thereference mirror holding means.

4. The device for adjusting the angle of inclination of a referencemirror for interferometers according to claim 2 wherein the guide slotis provided in the tubular portion of the support means, and theprojection means is provided on the lens tube.

5. The device for adjusting the angle of inclination of a referencemirror for interferometers according to claim 4 further comprisingresilient means between the reference mirror holding means and thesupport means.

1. A device for adjusting the angle of inclination of a reference mirrorfor interferometers comprising objective lens holding means; supportmeans mounted on the objective lens holding means; cooperable guide slotand projection means provided by the objective lens holding means andthe support means for relative sliding movement in a direction parallelto the optical axis of the objective lens; reference mirror holdingmeans; and adjusting means connecting the reference mirror holding meansto the support means for adjustment of the angle of inclination of thereference mirror holding means with respect to the support means andthereby with respect to the objective lens holding means.
 2. The devicefor adjusting the angle of inclination of a reference mirror forinterferometers according to claim 1 wherein the objective lens holdingmeans comprises a lens tube; wherein the support means includes atubular portion surrounding the lens tube and the adjusting meanscomprises a member threadably connected to one of the reference mirrorholding means and support means and is pivotally connected to the otherof the reference mirror holding means and support means.
 3. The devicefor adjusting the angle of inclination of a reference mirror forinterferometers according to claim 2 wherein the adjusting means furthercomprise hinge means connecting the support means and the referencemirror holding means.
 4. The device for adjusting the angle ofinclination of a reference mirror for interferometers according to claim2 wherein the guide slot is provided in the tubular portion of thesuppoRt means, and the projection means is provided on the lens tube. 5.The device for adjusting the angle of inclination of a reference mirrorfor interferometers according to claim 4 further comprising resilientmeans between the reference mirror holding means and the support means.